Separation of olefins from aluminum trialkoxides



United States Patent 3,350,360 SEPARATIQN 0F OLEFINS FROM ALUMINUM TRIALKOXIDES Giliord G. McClafiin, Ponca City, Okla, assignor to Continental Oil Company, Ponca City, Okla, a corporation of Delaware No Drawing. Filed Nov. 25, 1966, Ser. No. 596,830

8 Claims. (Cl. 260-677) ABSTRACT OF THE DISCLOSURE A mixture of aluminum trialkoxides having an average of about 24 to 36 carbons per alkyl, and olefins having an average of about 16 to 36 carbons, is separated by liquidliquid extraction using as solvent an aliphatic hydrocarbon having an average of about 20 to 25 carbons less than the trialkoxide.

Cross-reference to related application This is a continuation-in-part of the co-pending application of the present inventor, entitled, Separation of Olefins From Aluminum Trialkoxides, Serial No. 132,- 544, filed Aug. 21, 1961, now abandoned.

Disclosure This invention relates to a method of separating olefins from aluminum trialkoxides. Aluminum trialkyls are oxidized to aluminum trialkoxides which in turn are hydrolyzed to alcohols. The growth of aluminum trialkyls with ethylene produces olefins as by-product materials which are removed prior to the hydrolysis step. The removal of olefins may be accomplished by distillation, stripping, etc. Unfortunately,

such methods involve subjecting the aluminum trialkoxide to heat; consequently, there is a tendency for undesirable decomposition reactions to occur. The problem is further aggravated by the fact that the olefin is usually present in relatively small amounts, viz, up to about 9 percent by weight of the aluminum trialkoxide material; so care must be taken to avoid loss of the trialkoxide. Following an extensive investigation of this problem, quite surprisingly, I have discovered a simple, eliective and inexpensive solution.

An object of this invention is to provide a method of separating olefins from aluminum trialkoxides.

Another object of this invention is to provide a simple and eliective method of removing olefins from aluminum trialkoxides.

Other objects and advantages of this invention will become apparent from the following description and explanation thereof.

In accordance with this invention, aluminum trialkoxide containing a small amount of olefin is extracted with a hydrocarbon which contains on the average about 20 to 25 carbon atoms less than the average number of carbon atoms contained in the alkyl substituents of the aluminum trialkoxide.

The hydrocarbon employed as an extraction solvent is preferably saturated and aliphatic in type. The hydrocarbon includes the parafiinic hydrocarbons having a boiling point of about 36 to 215 C., preferably about 36 to 100 C. The hydrocarbon may be a single compound, such as: pentane, hexane, heptane, etc., or a mixture of hydrocarbons, such as a petroleum fraction, which has an A.S.T.M. initial boiling point of about 36 to 100 C. and an end point of about 85 to 100 C. Specific examples of petroleum fractions are petroleum ether, natural gasoline, light hydrocarbon fraction containing C to C hydrocarbons, etc. The hydrocarbon solvent may have a ICC boiling point of about 35 to 215 0., preferably about to 250 C. less than the olefin being extracted.

The hydrocarbon extraction solvent is sufiiciently close in property to the high boiling olefin so that substantially all or a significant amount is dissolved in the solvent upon extraction of the mixture of aluminum trialkoxide and olefin therewith. The aluminum trialkoxide, on the other hand, is substantially insoluble or significantly less soluble so that it remains essentially out of solution with re spect to the hydrocarbon solvent. The aluminum trialkoxide contains about 10 to 30 percent by weight, more usually about 10 to 20 percent by weight of olefin. The aluminum trialkoxide is extracted with hydrocarbon solvent in relative quantities of about 2 to 50 parts by weight of solvent per unit weight of aluminum trialkoxide, preferably about 5 to 15 parts by weight of solvent per unit weight of aluminum trialkoxide.

The aluminum trialkoxide of the present invention has the following formula:

/OR1 Al-O R2 wherein R R and R are the same or different alkyl groups, and the average of R R and R varies from about 24 to 36 carbon atoms, more usually about 26 to 34 carbon atoms. Specific examples of aluminum trialkoxide are aluminum tritetracosoxy, aluminum tripentacosoxy, aluminum trihexacosoxy, aluminum triheptacosoxy, aluminum octacosoxy, aluminum nonacosoxy, aluminum triacontoxy, aluminum trihentriacontoxy, aluminum tridotriacontoxy, etc., and admixtures thereof.

The aluminum trialkoxide is contaminated with olefinic material. The olefinic material may be a single compound or a mixture of compounds. The olefinic compounds may be monoor diunsaturated and may contain about 16 to 36 carbon atoms, more usually about 18 to 26 carbon atoms. The olefinic material is present with the aluminum trialkoxide in an amount of about 0.5 to 30 percent by weight, more usually about 1 to 9 percent by weight. Greater or less amounts of olefinic material may be present in the aluminum trialkoxide; however, the present invention is uniquely adapted for removal of relatively small quantities of olefinic material from the aluminum trialkoxide.

The extraction of olefin is usually conducted at a temperature of about 35 to 215 C., preferably about 35 to 100 C., and at a pressure of about 1 to 30 p.s.i.a., preferably about one atmosphere. The extraction time is about 1 to 24 hours, preferably about 4 to 12 hours. The conditions of extraction can be varied still more from What is described above and be Within the scope of the present invention. The extraction step can be accomplished by co-current or countercurrent flow, or by the simple batch technique. The countercurrent technique is preferred; however, any of the methods can be used for my invention.

For a fuller understanding of the present invention, reference will be had to the following specific examples.

Example .I

450 ml. of dry n-hexane and 18.2 gm. of aluminum trialkyl prepared by reacting aluminum triethyl with ethylene at C. and 1,500 p.s.i.g. to form a product having an average of 30 carbon atoms per substituent and which was oxidized with air at 5070 C. until oxidation ceased were added to a Soxhlet extractor equipped with a calcium chloride drier. The thimble employed was a Green No. 703. The extraction occurred for 24 hours. The hexane soluble portion was found to be 7.2 grams.

The hexane insoluble material Was hydrolyzed by means of diulte HCl. The organic layer after hydrolysis was found to contain 33.4 percent hydrocarbon. The aluminum alkoxide when hydrolyzed with the solvent extraction step omitted yielded a product containing 45.0 percent hydrocarbon. Analysis of this hydrocarbon material discloses that about 33 percent is saturated hydrocarbons and about 12 percent is olefins.

Example 2 50 grams of the aluminum trialkoxide described in Example 1 and 400 ml. of petroleum ether having an A.S.T.M. boiling range of 30 to 60 C. were charged to the same extractor as used in Example 1. The extraction took 32 hours. The solvent-soluble fraction was hydrolyzed with 25 percent HCl to give an organic phase containing 61.5 percent hydrocarbon. The solvent insoluble fraction was also hydrolyzed with 25 percent HCl and the organic phase contained 30.8 percent hydrocarbon.

Example 3 450 ml. of dry n-hexane and 18.2 gm. of aluminum trialkyl prepared by reacting aluminum triethyl with ethylene at 120 C. and 1,500 p.s.i.g. to form a product (same as Example 1) having an average of 30 carbon atoms per substituent and which is oxidized with air at 50-70" C. until oxidation ceased is added to a Soxhlet extractor equipped with a calcium chloride drier. The thimble employed is a Green No. 703. The extraction is continued for 24 hours. The hexane soluble portion is found to be 7.2 grams. The hexane insoluble material is hydrolyzed by means of dilute HCl. The organic layer is found to contain 33.4 percent hydrocarbon. Analysis of this hydrocarbon material discloses that it is essentially saturated hydrocarbons with less than about 2 percent olefins. It is believed that the saturated hydrocarbons result from the hydrolysis of unoxidized aluminum alkyls.

It is apparent from the foregoing examples that the process of this invention produces a product which is greatly reduced in olefin content.

Having thus described the invention by providing specific examples thereof, it is to be understood that no undue limitations or restrictions are to be drawn by reason thereof and that many variations and modifications are within the scope of the invention.

I claim:

1. A process which comprises extracting olefinic material having an average number of carbon atoms of about 16 to 36 from an aluminum trialkoxide having alkyl substituents containing an average number of carbon atoms of about 24 to 36 by means of liquid-liquid extraction with an aliphatic hydrocarbon having an average number of carbon atoms of about 20 to 25 less than said aluminum trialkoxide.

2. The process of claim 1 wherein the temperature of extraction is about 35 to 215 C. and the pressure about 1 to 30 p.s.i.a.

3. The process of claim 1 wherein the aliphatic hydrocarbon is a petroleum fraction.

4. The process of claim 1 wherein the aliphatic hydrocarbon is petroleum ether.

5. The process of claim 1 wherein the aliphatic hydrocarbon is n-hexane.

6. The process which comprises extracting from aluminum trialkoxide having an average number of carbon atoms per substituent in the order of about 30 and contaminated with not more than about 30 percent of olefin having the same average number of carbon atoms by liquid-liquid extraction with n-hexane to remove a substantial amount of olefin from the aluminum trialkoxide.

7. A process which comprises extracting olefinic material having an average number of carbon atoms of about l636 from an aluminum trialkoxide having alkyl substituents containing an average number of carbon atoms of about 24-36 by means of liquid-liquid extraction with an aliphatic hydrocarbon having a boiling point of about 36215 C.

8. A process according to claim 7 wherein the boiling point of the aliphatic hydrocarbon is about 36lOO C.

References Cited UNITED STATES PATENTS 2,863,895 6/1956 Kirshenbaum et al. 260448 2,892,858 6/1959 Ziegler 260448 3,062,857 1/1960 Acciarri et al. 260448 DELBERT E. GANTZ, Primary Examiner.

I. D. MYERS, Assistant Examiner. 

6. THE PROCESS WHICH COMPRISES EXTRACTING FROM ALUMINUM TRIALKOXIDE HAVING AN AVERAGE NUMBER OF CARBON ATOMS PER SUBSTITUENT IN THE ORDER OF ABOUT 36 AND CONTAMINATED WITH NOT MORE THAN ABOUT 30 PERCENT OF OLEFIN HAVING THE SAME AVERAGE NUMBER OF CARBON ATOMS BY LIQUID-LIQUID EXTRACTION WITH N-HEXANE TO REMOVE A SUBSTANTIAL AMOUNT OF OLEFIN FROM THE ALUMINUM TRIALKOXIDE. 